U.S. patent application number 12/670905 was filed with the patent office on 2010-09-30 for crystalline form ii of 7-(dimethoxy-methyl) camptothecin, its use as intermediate and products obtained therefrom.
This patent application is currently assigned to SIGMA-TAU INDUSTRIE FARMACEUTICHE RIUNITE S.P.A.. Invention is credited to Silvia Armaroli, Elena Badaloni, Walter Cabri, Fabrizio Giorgi, Giuseppe Marazzi, Mauro Marzi.
Application Number | 20100249414 12/670905 |
Document ID | / |
Family ID | 38865681 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100249414 |
Kind Code |
A1 |
Cabri; Walter ; et
al. |
September 30, 2010 |
CRYSTALLINE FORM II OF 7-(DIMETHOXY-METHYL) CAMPTOTHECIN, ITS USE
AS INTERMEDIATE AND PRODUCTS OBTAINED THEREFROM
Abstract
This invention relates to a process for preparing a crystalline
form of
(4S)-11-(dimethoxymethyl)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizin-
o[1,2-b]qui-noline-3,14(4H,12H)-dione (also named
7-(dimethoxy-methyl)camptothecin). With the provision of a
particular crystallization step, in appropriate way, a new
crystalline form of the above compound is obtained. The process for
the preparation of the polymorph Form II comprises transforming
camptothecin to the corresponding
7-(dimethoxy-methyl)-camptothecin, and crystallizing it from
methanol.
Inventors: |
Cabri; Walter; (Rozzano,
IT) ; Marzi; Mauro; (Roma, IT) ; Giorgi;
Fabrizio; (Ardea, IT) ; Badaloni; Elena;
(Roma, IT) ; Armaroli; Silvia; (Gallo Poggio
Renatico, IT) ; Marazzi; Giuseppe; (Milano,
IT) |
Correspondence
Address: |
LUCAS & MERCANTI, LLP
475 PARK AVENUE SOUTH, 15TH FLOOR
NEW YORK
NY
10016
US
|
Assignee: |
SIGMA-TAU INDUSTRIE FARMACEUTICHE
RIUNITE S.P.A.
Roma
IT
|
Family ID: |
38865681 |
Appl. No.: |
12/670905 |
Filed: |
July 22, 2008 |
PCT Filed: |
July 22, 2008 |
PCT NO: |
PCT/EP2008/059597 |
371 Date: |
March 3, 2010 |
Current U.S.
Class: |
546/48 |
Current CPC
Class: |
C07D 491/22
20130101 |
Class at
Publication: |
546/48 |
International
Class: |
C07D 471/20 20060101
C07D471/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2007 |
EP |
07113597.4 |
Claims
1. Polymorph Form II of 7-(dimethoxy-methyl)camptothecin.
2. The polymorph Form II according to claim 1, which undergoes
degradation starting from the temperature of about 160.degree.
C.
3. The polymorph Form II according to claim 1, wherein said
polymorph shows an X-ray powder diffraction pattern having the
following characteristic peaks expressed in degrees 2.THETA..+-.0.2
TABLE-US-00005 Degrees 2-Theta Relative intensity (%) 6.3 20 8.7 21
10.6 100 13.6 23 16.3 18 16.7 20 19.5 13 21.2 21 25.3 22 27.4
17
4. The polymorph Form II according to claim 1, which shows an X-ray
powder diffraction pattern as shown in FIG. 1.
5. The polymorph Form II according to claim 1, which shows an IR
spectrum (KBr) with the following main peaks: TABLE-US-00006
Frequency (cm.sup.''1) Intensity (% T) 3518 53 2989 65 2936 65 1744
21 1660 21 1463 50 1155 31 1060 23 769 37
6. The polymorph Form II according to claim 1 which shows an IR
spectrum as shown in FIG. 2.
7. The polymorph Form II according to claim 1, which is
substantially free from aldehyde impurity.
8. A solvate of the polymorph Form II of claim 1.
9. A process for the preparation of the polymorph Form II of claim
1, comprising the following steps: a. oxidizing position 7 of
camptothecin or a derivative thereof to obtain the corresponding
7-keto-camptothecin or 7-keto-camptothecin derivative; b. treating
7-keto-camptothecin or 7-keto-camptothecin derivative obtained in
step a) with methanol, in the presence of an acid to obtain a
first, acid methanol reaction mixture; c. neutralizing said first,
acid methanol reaction mixture from step b) to obtain a second,
substantially neutral methanol reaction mixture; d. adding water to
said second, substantially neutral methanol reaction mixture, to
obtain a precipitate; e. separating said precipitate of step d) to
obtain an isolated precipitate; f. crystallizing said isolated
precipitate of step e) from methanol to give said polymorph.
10. Process according to claim 9, wherein the oxidizing step of
step a) is performed with a first oxidizing system and a second
oxidizing system.
11. Process according to claim 10, wherein said first oxidizing
system is 30% H.sub.2O.sub.2/Fe(II) salt and said second oxidizing
system is selected from the group consisting of acetic acid,
CrO.sub.3, and MnO.sub.2.
12. Process according to claim 11, wherein said first oxidizing
system is 30% H.sub.2O.sub.2/iron sulphate and said second
oxidizing system is manganese dioxide.
13. Process according to claim 9, wherein said first, acid methanol
reaction mixture of step b) is selected from the group consisting
of distilled methanol and 30% water/70% methanol solution.
14. Process according to claim 9, wherein said acid of step b is
selected from the group consisting of H.sub.2SO.sub.4,
CH.sub.3COOH, H.sub.3PO.sub.4, HCl SOCl.sub.2, COCl.sub.2,
CH.sub.3SO.sub.2OH, CH.sub.3PhSO.sub.2OH, CF.sub.3COOH,
CF.sub.3SO.sub.3H.
15. Process according to claim 14, wherein said acid of step b) is
98% H.sub.2SO.sub.4.
16. Process according to claim 14, wherein said acid is in a
concentration of 10% v/v.
17. Process according to claim 9, wherein, after step f) said
crystallized polymorph Form II is dried under vacuum at 40.degree.
C. overnight.
18. Use of the polymorph Form II of claim 1 in a process for the
preparation of a camptothecin derivative.
19. A process for the preparation of a camptothecin derivative in
which the polymorph Form II of claim 1 is used.
Description
[0001] The present invention relates to the field of organic
chemistry, in particular to compounds useful as intermediates in
processes for the preparation of active ingredients in
medicine.
FIELD OF THE INVENTION
[0002] This invention relates to a process for preparing a
crystalline form of
(4S)-11-(dimethoxymethyl)-4-ethyl-4-hydroxy-1H-pyrano[3',4':
6,7]indolizino[1,2-b]qui-noline-3,14(4H,12H)-dione (CAS n
84017-99-2), also named 7-(dimethoxy-methyl)camptothecin. With the
provision of a particular crystallization step, in appropriate way,
a new crystalline form of the above compound is obtained.
BACKGROUND OF THE INVENTION
[0003] Camptothecin is an alkaloid, which demonstrated a wide
spectrum of antitumor activity, in particular against colon tumors,
other solid tumors and leukemias, and the first clinical trials
were performed in the early 70's.
[0004] Since Camptothecin (CPT) has low water solubility and is
rather toxic, a number of derivatives were proposed in the art in
order to make available better drugs, in particular with lower
toxicity and higher water solubility.
[0005] Many camptothecin derivatives were prepared and made
available in the art through several synthetic routes.
[0006] The quality of the final product, such as its purity level
or the easiness of isolation may depend also on the synthetic route
and the kind of intermediate products.
[0007] In patent EP 1 044 977 and in Dallavalle S. et al., J. Med.
Chem. 2001, 44, 3264-3274, camptothecin derivatives bearing an
alkyloxime O-substituted at position 7 and endowed with antitumor
activity higher than the compound of reference topotecan are
described. Moreover these camptothecin derivatives bearing an imino
group on position 7, also show an improved therapeutic index. One
of the preferred molecules is 7-t-butoxyiminomethylcamptothecin
(CPT 184) and known under the INN name Gimatecan.
[0008] 7-(dimethoxy-methyl)camptothecin is disclosed in EP 0 056
692 and in Sawada, S., et al., Chemical & Pharmaceutical
Bulletin (1991), 39(10), 2574-80.
[0009] This compound is used in different patents as intermediate
in the synthesis of camptothecin derivatives.
[0010] 7-(dimethoxy-methyl)-camptothecin can be prepared by
ordinary acetalization of camptothecin 7-aldehyde, for example by
heating camptothecin 7-aldehyde in hot methanol in the presence of
an acid. Alternatively, this compound can be prepared in a single
step by treating 7-hydroxymethylcamptothecin with an acid in the
presence of methanol, see the above mentioned EP 0 056 692.
[0011] Acetalization is an equilibrium reaction and the starting
aldehyde can be present in a certain amount. Moreover, acetals can
be converted in the starting aldehyde in the presence of acids.
[0012] It is well-known that aldehydes are not endowed with high
stability and they tend to polymerize giving side products which
are difficult to eliminate from reaction mixtures and affect the
purity of the final product.
[0013] The absence of the aldehyde allows crystallization and
elimination of other unwished impurities, which can be present both
in the starting material and derive from the reaction.
[0014] For example, 9, 10 and 11 hydroxy- and methoxy-camptothecins
(see below general formula 1), mappicine (see below general formula
2), and their derivatives are side derivatives produced in the
reaction of formation of 7-(dimethoxy-methyl)camptothecin.
##STR00001##
[0015] WO2006/067092 discloses a stereoselective process for the
preparation of crystalline forms of Gimatecan. This process allows
the stereoselective preparation of Gimatecan.
[0016] With the addition of further dissolution and precipitation
steps carried out in appropriate different solvent mixtures, four
new crystalline forms of Gimatecan are also obtainable by using the
same stereoselective process.
[0017] 7-(dimethoxy-methyl)camptothecin is only mentioned as
starting material, with no characterization.
[0018] WO03/101995 discloses camptothecins with a modified lactone
ring and 7-(dimethoxy-methyl)camptothecin is used as intermediate
in the synthesis of the final products.
7-(dimethoxy-methyl)camptothecin preparation is provided as
purified from column chromatography and as a yellow solid with m.p.
201.degree. C. (dec.). Product yield is 55%.
[0019] In the above mentioned Chemical & Pharmaceutical
Bulletin (1991), 39(10), 2574-80 and in EP 0 056 692, the
7-(dimethoxy-methyl)camptothecin is disclosed as purified from
column, m.p. 222-224.degree. C. (dec.) and needle crystal.
[0020] Pharmaceutical legislations are stricter and stricter on
safety issues concerning drug manufacturing. One aspect is Good
Manufacturing Practice (GMP, see for Example EMEA and FDA
Guidelines) and a sensitive topic is represented by standardization
of intermediate compounds and impurity levels.
[0021] There is still the need of a form of
7-(dimethoxy-methyl)camptothecin of higher purity and that can be
used for subsequent preparation of camptothecin derivatives to be
used as drugs, meeting the severe regulatory requirements
easier.
[0022] From a regulatory point of view, a high purity intermediate
means a higher purity final product, with more severe
specifications, therefore lesser quality variability. This latter
aspect is requested and appreciated by Regulatory Authorities.
Moreover, crystallization of an intermediate product represents an
optimal purification step, allowing a better control of final
quality, thus meeting GMP requirements easier and facilitating the
whole production process. In this context, WO/03101995 does not
teach any crystallization.
[0023] Another, additional need in synthesis of drugs is the
stability of intermediate compounds. Stability is a desirable and
necessary property for the intermediate compounds, since they are
able to withstand chemical reaction conditions, in particular
temperatures, without undergoing degradation or decomposition. More
in particular, a high melting point, especially for those compounds
which melt with decomposition, is recommended, as to avoid the
presence in the reaction mixture of degradation side products,
which make purification of the final product (the drug) much more
difficult, even impossible.
SUMMARY OF THE INVENTION
[0024] We have now surprisingly found a new form of
(4S)-11-(dimethoxymethyl)-4-ethyl-4-hydroxy-1H-pyrano[3',':6,7]indolizino-
[1,2-b]quinoline-3,14(4H,12H)-dione, or otherwise named in this
description and claims 7-(dimethoxy-methyl)camptothecin (also named
Form II or with our code ST2337) which provides an improvement in
the state of the art of camptothecin derivative preparation.
[0025] In particular, the present invention provides a polymorph of
7-(dimethoxy-methyl)camptothecin which is endowed with higher
purity, in particular with respect to side products of aldehyde
type and derivatives thereof.
[0026] Therefore, it is an object of the present invention the
crystalline form of 7-(dimethoxy-methyl)camptothecin Form II.
[0027] Another object of the present invention is a process for the
preparation of the above crystalline form.
[0028] A further object of the present invention is the use of the
crystalline form of 7-(dimethoxy-methyl)camptothecin as
intermediate in a process for the preparation of camptothecin
derivatives.
[0029] These and other objects will be illustrated in detail in the
foregoing description, also by means of Figures and Examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In the attached drawings:
[0031] FIG. 1 represents the X-ray powder diffractogram of the
polymorph Form II of the present invention, using a computer
controlled XRD powder diffraction apparatus and examined under
inert atmosphere. Diffractometry conditions were 40 KV.times.40 mA
CuK.alpha..
[0032] FIG. 2 represents the diffuse reflectance FT-IR spectrum of
the compound of the present invention, the polymorph Form II, in
KBr with a Thermo Nicolet spectrometer model Avatar 370 DTGS.
[0033] FIG. 3 represents thermal behaviour of the compound of the
invention measured by a melting range apparatus.
[0034] FIG. 4 represents differential scanning calorimetry (DSC)
analysis of the polymorph Form II.
[0035] FIG. 5 represents differential scanning calorimetry (DSC)
analysis of the polymorph Form II with a different scanning
speed.
[0036] FIG. 6 shows FT-IR spectrum of
7-(dimethoxymethyl)camptothecin polymorph of the prior art (Form
I).
[0037] FIGS. 7-9 show compared FT-IR spectra of
7-(dimethoxymethyl)camptothecin polymorph according to the present
invention (Form II) and of the prior art (Form I).
[0038] FIG. 10 shows X-ray powder diffractogram of the polymorph
Form I of the prior art.
[0039] FIG. 11 shows the comparison between XRPD spectra of Form
II, the 7-(dimethoxymethyl)camptothecin polymorph according to the
present invention, and polymorph Form I of the state of the
art.
[0040] FIG. 12 shows thermal behaviour of
7-(dimethoxy-methyl)camptothecin form I.
DETAILED DESCRIPTION OF THE INVENTION
[0041] The polymorph Form II of 7-(dimethoxy-methyl)-camptothecin
of the present invention is characterized by the physico-chemical
parameters provided in this description.
[0042] A particular advantage of the polymorph Form II according to
the present invention is to be substantially free from aldehyde
impurities and derivatives thereof.
[0043] By the term "substantially free" it is intended that the
compound of the present invention contains no aldehyde impurities
and derivatives thereof, or at least no detectable amounts, or at
least amounts below the admitted limits stated by National or
European Pharmacopoeias.
[0044] By the term "aldehyde impurities and derivatives thereof" it
is intended a 7-formyl-camptothecin, said camptothecin being
optionally substituted and/or having a modified lactone, an
aldehyde polymer product, or any derivative of aldehyde.
[0045] The polymorph Form II of 7-(dimethoxy-methyl)camptothecin is
prepared by transformation of camptothecin, through its
7-keto-derivative:
##STR00002##
[0046] The process according to the present invention comprises the
following steps:
a. oxidizing position 7 of camptothecin or a derivative thereof to
obtain the corresponding 7-keto-camptothecin or 7-keto-camptothecin
derivative; b. treating 7-keto-camptothecin or 7-keto-camptothecin
derivative obtained in step a) with methanol, in the presence of an
acid to obtain a first, acid methanol reaction mixture; c.
neutralizing said first, acid methanol reaction mixture from step
b) to give a second, substantially neutral methanol reaction
mixture; d. adding water to said second, substantially neutral
methanol reaction mixture, to obtain a precipitate; e. separating
said precipitate of step d) to obtain an isolated precipitate; f.
crystallizing said isolated precipitate of step e) from methanol to
give said polymorph.
[0047] The oxidizing step of step a) can be performed according to
well known methods, see for example U.S. Pat. No. 6,194,579.
[0048] In a preferred embodiment of the present invention,
oxidizing step is performed with a first oxidizing system and a
second oxidizing system. In a further preferred embodiment, said
first oxidizing system is 30% H.sub.2O.sub.2/Fe(II) salt and said
second oxidizing system is selected from the group consisting of
acetic acid, CrO.sub.3, and MnO.sub.2. In the most preferred
embodiment, said first oxidizing system is 30% H.sub.2O.sub.2/iron
sulphate and said second oxidizing system is manganese dioxide (see
WO03/101995).
[0049] Step b) is also a well-known procedure for obtaining acetals
of aldehyde compounds. In a preferred embodiment, said first, acid
methanol reaction mixture is selected from the group consisting of
distilled methanol and a low water methanol mixture, for example
30% water/70% methanol solution.
[0050] The acid used in step b) can be any organic or inorganic
acid which does not interfere with the progress of reaction or with
the stability of the starting material or of the final product.
Typically, said acid is selected from the group consisting of
H.sub.2SO.sub.4, CH.sub.3COOH, H.sub.3PO.sub.4, HCl SOCl.sub.2,
COCl.sub.2, CH.sub.3SO.sub.2OH, CH.sub.3PhSO.sub.2OH, CF.sub.3COOH,
CF.sub.3SO.sub.3H. The preferred acid is 98% H.sub.2SO.sub.4 in a
concentration of 10% v/v.
[0051] Steps c), d) and e) are also carried out according to common
practice and the person of ordinary skill in the art will have no
difficulty in selecting the proper conditions, equipments and any
other element for performing these steps.
[0052] Step f), which is essential for achieving the final product,
is also a common step of crystallization that can be carried out by
the normal chemistry practitioner, either on lab scale or in
industrial scale, just selecting the proper conditions, such as
volumes, temperatures, time.
[0053] Isolation of the polymorph Form II of
7-(dimethoxy-methyl)-camptothecin is carried out according to
normal practice and this step need no further explanation.
[0054] Preferably, the final product is dried in order to eliminate
solvent traces.
[0055] A further object of the present invention are solvates of
the above polymorph Form II of
7-(dimethoxy-methyl)-camptothecin.
[0056] Camptothecin is a commercial product or can be prepared
according to literature methods, see for example U.S. Pat. Nos.
5,053,512, 4,894,456, 5,405,963 and 6,982,333,
[0057] Starting camptothecin is suspended into methanol (0.5 to
10%; preferably 1.5% solution w/v). The solution or suspension is
kept at a temperature ranging from -10 to 80.degree. C. (preferably
0 to 50.degree. C.) and added with a mineral or organic acid,
preferably H.sub.2SO.sub.4 90 to 98% (preferably 96%) (1% to 30%,
preferably 10% v/v), and at the presence of a suitable first
oxidizing system (for example 30% H.sub.2O.sub.2/Fe(II) salts),
then a second oxidizing agent (for example acetic acid, CrO.sub.3,
MnO.sub.2) to obtain the desired product. A preferred first
oxidizing system is iron sulphate/hydrogen peroxide. A preferred
second oxidizing system is manganese dioxide.
[0058] The dried solid is then suspended in freshly distilled or
with low water content methanol (30% solution) and a mineral or
organic acid ranging between catalytic to stoichiometric amounts
are added. The acid can be selected from the preferred group
consisting of H.sub.2SO.sub.4, CH.sub.3COOH, H.sub.3PO.sub.4, HCl
SOCl.sub.2, COCl.sub.2, CH.sub.3SO.sub.2OH (MsOH),
CH.sub.3PhSO.sub.2OH (TsOH), CF.sub.3COOH, CF.sub.3SO.sub.3H. Other
acids can be used with similar results. Preferred acid and its
concentration are 10% v/v of H.sub.2SO.sub.4 98%
[0059] After a suitable time, such as 2-6 h, the solution is
neutralized until about pH 6 with a suitable base, such as aqueous
NaOH, KOH or Na.sub.2CO.sub.3.
[0060] Then water is added to obtain a yellow precipitate which is
isolated, preferably by filtration and crystallized again from
MeOH.
[0061] The obtained solid is finally dried, for example under
vacuum at 40.degree. C. overnight.
[0062] The polymorph Form II is suitable as intermediate for the
preparation of camptothecin derivatives, such as the ones disclosed
in EP 0 056 692, in particular, and preferably the ones disclosed
in WO03/101995 and any other camptothecin derivative for use as in
the treatment of diseases responding to inhibition of Topoisomerase
I, such as for example tumors, HIV infections and parasitic
infections.
[0063] In an exemplary embodiment of the invention, the polymorph
Form II of 7-(dimethoxy-methyl)-camptothecin was used as
intermediate product for the preparation of the compounds disclosed
in WO03/101995.
[0064] The following examples further illustrate the invention.
Example 1
[0065] To a suspension of 1.53 g (4.4 mmol) of camptothecin in 92
ml of methanol, cooled with an ice bath under stirring, were added
slowly 9.2 ml of H.sub.2SO.sub.4 96%, keeping the temperature of
the mixture below 50.degree. C. The suspension thus obtained was
heated to reflux temperature; on reaching 50.degree. C., 46 mg of
FeSO.sub.4 7H.sub.2O were added and then 3 ml of H.sub.2O.sub.2 30%
dropwise, keeping the reaction at reflux temperature. The reaction
was stirred for 2 hours, checking for disappearance of the starting
product by TLC. On completion of the reaction, the suspension was
cooled to 25.degree. C. and 2.8 g of MnO.sub.2 were added; the
mixture was stirred for 2 hours, checking for disappearance of the
intermediate product by TLC. The suspension was then filtered
through a layer of Celite placed on a Gooch filter.
[0066] The reaction mixture was concentrated under reduced pressure
and the solid obtained was suspended in freshly distilled or low
water content methanol and H.sub.2SO.sub.4 (98%) (4.4
equivalent).
[0067] The suspension was stirred for 6 h and then was neutralized
until about pH 6 with 1N NaOH solution.
[0068] Then water was added to obtain a yellow precipitate which
was isolated by filtration. The solid was crystallized from MeOH
and dried under vacuum at 40.degree. C. overnight.
Solid State Characterization of 7-(Dimethoxy-Methyl)Camptothecin
(Form II)
X-Ray Powder Diffractrometry
[0069] The X-ray powder diffractogram on about 15 mg of ground
powder was obtained using a computer controlled XRD powder
diffraction apparatus and examined under inert atmosphere.
[0070] The tube conditions were 40 KV.times.40 mA CuK.alpha., the
windows used were aperture 0.3.degree., and closing 0.15.degree..
The time for each step scan was 7 s, the 2-.theta. range was
5.degree.-35.degree..
[0071] After the acquisition, an accurate analysis of the spectrum
was performed adopting a procedure for the peak evaluation taking
into account both the minimum peak width and an estimated amount of
disordered part. It is concluded that the sample is
crystalline.
[0072] The characteristic main diffraction peaks are given in the
following table 1.
TABLE-US-00001 TABLE 1 Degrees 2-Theta .+-. 0.2 Relative intensity
(%) 6.3 20 8.7 21 10.6 100 12.9 8 13.6 23 16.3 18 16.7 20 18.6 6
19.5 13 21.2 21 23.9 6 25.3 22 26.2 9 27.3 17 28.5 4 28.9 4 29.5 4
30.5 4 31.4 9 32.7 2
[0073] FIG. 1 shows X-ray powder diffractogram of
7-(dimethoxy-methyl)camptothecin (form II).
[0074] The most representative peaks are given in Table 2
below.
TABLE-US-00002 TABLE 2 Degrees 2-Theta Relative intensity (%) 6.3
20 8.7 21 10.6 100 13.6 23 16.3 18 16.7 20 19.5 13 21.2 21 25.3 22
27.4 17
IR Spectrum
[0075] The diffuse reflectance FT-IR spectrum of
7-(dimethoxy-methyl)camptothecin form II was collected on a 2%
sample in KBr with a Thermo Nicolet spectrometer model Avatar 370
DTGS.
[0076] In the following table 3 main signals (cm.sup.-1)
characteristic of this crystalline form are reported.
TABLE-US-00003 TABLE 3 Frequency (cm.sup.-1) Intensity (% T) 3518
53 2989 65 2936 65 1744 21 1660 21 1463 50 1155 31 1060 23 769
37
[0077] FIG. 2 shows IR Spectrum (in KBr) of
7-(dimethoxy-methyl)camptothecin (form II)
Thermal Behaviour
[0078] 7-(dimethoxy-methyl)camptothecin undergoes degradation
starting from the temperature of about 160.degree. C., measured by
a suitable melting range apparatus (Mettler TG 50, temperature ramp
from 25.degree. C. to 600.degree. C. at 10.degree. C./min., see
FIG. 3) and confirmed by the differential scanning calorimetry
analysis (DSC mod. Mettler DSC 30, temperature ramp from 25.degree.
C. to 160.degree. C. at 10.degree. C./min., see FIG. 4) which
indicates that no melting phenomena occurred before 160.degree. C.
The same experiment was repeated at different heat rump (20.degree.
C./min) giving a value of decomposition temperature at
173.56.degree. C. (see FIG. 5).
HPLC-MS Analysis
[0079] An HPLC-MS analysis was performed in order to study the
impurity profile of 7-(dimethoxy-methyl)camptothecin. In the
following described experimental conditions no peak with a
molecular weight compatible with aldehyde has been found.
Experimental Conditions:
Equipment:
[0080] Surveyor LC, micro pump, Autosampler--Thermo; [0081] LCQ
DecaXP Plus ion trap mass spectrometer with ESI (+) interface,
Thermo;
Column:
[0081] [0082] Inertsil ODS-3 (5 .mu.m, 150.times.4.6 mm ID)--GL
Sciences Inc.; Mobile phase: [0083] A: H.sub.2O+HCOOH 0.1%; [0084]
B: H.sub.2O/CH.sub.3CN 10/90 v/v+HCOOH 0.1%; Gradient elution:
[0085] A/B 70/30 to 100% B in 20 minutes; Flow rate: [0086] 1.0
mL/min;
Detection:
[0086] [0087] ESI (+) interface: capillary temp. 300.degree. C.;
[0088] Shield gas flow (N.sub.2): 70; [0089] Auxiliary gas flow
(N.sub.2): 10; [0090] Capillary voltage: 3 V; Source voltage:
[0091] 5 kV; Source current: [0092] 80 .mu.A; Tube lens offset:
[0093] 20 V; Acquisition range: [0094] 200-600 amu.
Example 2
Comparative Example
[0095] This Example was conducted in order to ascertain the
differences between the crystal form of the
7-(dimethoxy-methyl)camptothecin obtained by chloroform/n-hexane
crystallization, as described by the above mentioned Sawada et al.,
1994, and named herein Form I) and the
7-(dimethoxy-methyl)camptothecin obtained according to the present
invention, named Form II.
[0096] The results (FT-IR, powder x-ray and TGA) showed the
existence of differences between the two forms and that the form II
is more stable (it decomposes at higher temperature) in comparison
with the other form I.
[0097] The aim of this example is to verify that the form described
in the cited article, crystallized by chloroform and n-hexane
(named Form I), is different from Form II of the present
invention.
Equipments
[0098] FT-IR Spectrophotometer THERMO (Nicolet 5700) connected to a
PC via the OMNIC analysis software; Drying oven;
Stirring Plate;
[0099] TGA thermobalance PerkinElmer (Analytical dept. Lab. MASC);
NMR Varian (Analytical dept. Lab. MASC);
Powder X-Ray (ISMAC).
Sample and Solvent
[0100] 7-(dimethoxy-methyl)camptothecin: According to Example
above. n-hexane: MERCK (Batch K37503267 725) (Boiling Point
69.degree. C.).
Chloroform: Sigma Aldrich (Batch 01635EC-344) (Boiling Point
61.degree. C.).
[0101] The compound 7-(dimethoxy-methyl)camptothecin was prepared
according to steps a)-e) described above and in Example 1.
Crystallisation Technique
[0102] About 130 mg of 7-(dimethoxy-methyl)camptothecin were
solubilised in about 15 ml of chloroform, in a brown round bottom
flask, under magnetic stirring. After complete solubilisation of
the solid, the solution was filtered on Nalgene 0.2 .mu.m filter,
and then added with about 10 ml of n-hexane until to obtain
complete precipitation.
[0103] The obtained crop was separated by filtration and dried with
vacuum pump.
Characterization of 7-(Dimethoxy-Methyl)Camptothecin Form I
[0104] The solid obtained was identified by NMR spectroscopy, using
a NMR 500 spectrometer (solid solubilized in DMSO) and
characterized by FT-IR (FIGS. 6, 7, 8 and 9), XRPD (FIG. 10) and
TGA (FIG. 12).
[0105] The NMR is in compliance with the structure of
7-(dimethoxy-methyl)camptothecin.
[0106] The comparison between infrared spectra of Form II and Form
I showed a significant difference between the region 3600-2700
cm.sup.-1, around 1700 cm.sup.-1 and between 1600-800 cm.sup.-1
(show FIGS. 7, 8 and 9).
[0107] The FT-IR Match between these two forms is 35.05%.
TABLE-US-00004 TABLE 4 2.THETA. values of X-ray powder
diffractogram for 7-(dimethoxy-methyl)camptothecin Form I Degrees
2-Theta Relative intensity (%) 5.75 33.65 7.25 20.19 8.75 100 13.4
36.53 14.25 43.26 14.9 20.19 15.2 25 15.65 35.57 15.85 36.53 17
95.19 17.3 66.34 17.75 43.26 18.2 62.5 20.4 36.53 22.05 52.88 22.7
35.57 23.55 50 26.45 29.80 28.95 26.92
[0108] The comparison between XRPD spectra of Form II and Form I
showed a significant difference (see FIG. 11). In fact, the most
characteristic diffraction peaks of Form II are at 6.3, 10.6, 19.5
and 25.3 degree (while those relatives of Form I are at 5.75, 18.2,
and 23.55 degree).
Thermal Behaviour
[0109] 7-(dimethoxy-methyl)camptothecin form I undergoes
degradation starting from the temperature of 123.38.degree. C. (the
step around 100.degree. C. is due to variation of heating ramp),
measured by a suitable melting range apparatus (Mettler TG 50,
temperature ramp from 25.degree. C. to 600.degree. C. at 20.degree.
C./min., see FIG. 12) and confirmed by the differential scanning
calorimetry analysis (DSC mod. Mettler DSC 30, temperature ramp
from 25.degree. C. to 160.degree. C. at 20.degree. C./min.) which
indicates that no melting phenomena occurred.
CONCLUSION
[0110] The study of crystal form of the
7-(dimethoxy-methyl)camptothecin obtained by chloroform/n-hexane
(Form I) and Form II, showed significant differences between
them.
[0111] The DSC-TGA analysis showed that this Form I is less stable
in comparison with Form II, in fact the decomposition temperature
of Form II is 173.56.degree. C. while for the form I is
123.38.degree. C.
[0112] Both solid forms of 7-(dimethoxy-methyl)camptothecin have
almost thermal behaviour when the melting points were performed by
a very similar instrument used by Sawada in 1991. In fact using a
BUCHI 535 melting point we are not able to appreciate the
decomposition and the melting phenomena can be confused with
decomposition. With Buchi system we registered a melting point
closed to 222-224.degree. C. for form 1 and 224-226.degree. C. for
form II.
* * * * *